Amalgamation process

ABSTRACT

METHODS FOR AMALGAMATING IRON, PLATINUM, AND FERROUS ALLOYS, BY ACID CLEANING THE MATERIAL TO BE AMALGAMATED AND PERMITTING MOISTURE TO REMAIN OR FORM ON THE CLEANED METAL PRIOR TO DIPPING IN AMALGAM.

United States Patent 3,578,439 AMALGAMATION PROCESS Maximillian R.Merriman, Upper Hibernia Road, Rockaway, NJ. 07866 No Drawing. FiledJuly 2, 1968, Ser. No. 741,891 Int. Cl. 'C22c 5/00, 7/00, 35/00 U.S. Cl.75-129 10 Claims ABSTRACT OF THE DISCLOSURE Methods for amalgamatingiron, platinum, and ferrous alloys, by acid cleaning the material to beamalgamated and permitting moisture to remain or form on the cleanedmetal prior to dipping in amalgam.

The invention described herein may be manufactured, used, and licensedby or for the Government for governmental purposes without the paymentto me of any royalty thereon.

This invention relates to electrical contact devices and is directed toimproved methods for producing such devices by amalgamation, andparticularly, the amalgamation of ferrous materials.

It is well recognized that mercury has certain advantages over solidcontacts for opening and closing electric circuits. Being a fluid, itpresents a fresh surface for each contact closure and does not becomecorroded and pitted as a result of successive circuit interruptions. Onthe other hand, solid contacts have certain advantages. They can be madeof materials that are lighter than mercury and can be moved at higherspeeds. Also, it is possible to apply the forces of a magnetic fieldmore directly to solid contactoperating elements than to a mass ofmercury for ef fecting the desired circuit closures and openings.

Accordingly, it is common practice in the prior art manufacture ofswitches and relay contacts to employ solid contact-operating elementsand to provide means for covering the solid elements with a thin liquidcoating of mercury. However, when electrical contacts employingsubstantially pure iron or platinum are desired for use and hermeticallysealed devices, such, for example, as in glass to metal or ceramic tometal applications, no known procedures are available for amalgamatingthese metals.

Accordingly, it is an object of this invention to provide improvedmethods of forming electrical contacts for use in hermetically sealeddevices.

Another object of this invention is to provide improved methods forforming such contacts wherein platinum, or iron, or ferrous alloys areemployed.

Other objects and features of the invention will become apparent as theinvention is more fully hereinafter disclosed.

In accordance with these objects, I have discovered that iron andplatinum metals, and alloys of iron, may readily be amalgamated byanodically etching or dipping the metal or alloy in a suitable acid forcleaning thereof, and then amalgamating the metal or material in asuitable amalgam. Additionally, ferrous alloys may be amalgamatedreadily and economically by alloying with nickel or copper, for example,and then applying the steps of my invention to form the desiredelectrical contacts.

More specifically, I have discovered that pure iron or platinum,heretofore unwettable by mercury to form amalgam, may be wetted bymercury by cleaning the metal as aforedescribed and then treating thecleaned metal so as to permit a film of moisture to remain or form onthe material before dipping into an amalgam containing a minor portionof an alkali metal.

Although it is not intended that the invention be limited thereto, thereis set forth herein below for purposes of Patented May 11, 1971illustration, examples of procedures and values which may suitably beemployed in practicing my invention:

EXAMPLE I A stainless steel rod was placed in a beaker containing a 1%H01 solution for about 10 minutes. The rod was removed from the diluteacid and placed in an amalgam consisting of 0.4% by weight of potassium,the balance being substantially mercury. The moisture from the diluteacid, present on the steel rod, reacted with the alkali metal of theamalgam as evidenced by the evolution of bubbles, which was determinedto be nascent hydrogen which immediately reduced any undesirable oxidesformed on the steel rod while undergoing amalgamation. The rod wasmaintained in the amalgam for about 25 seconds and the resultant amalgamon the piece was adherent and could not be wiped off with a cloth withvigorous rubbing.

EXAMPLE II The procedure was generally similar to that described underExample I except high carbon steel drill was used. The resultantamalgamated piece was satisfactory.

EXAMPLE III platinum was dipped into an amalgam as described under'Example I and the resultant amalgamated piece was very satisfactory.

EXAMPLE IV An alloy comprising 45 nickel and 55 iron was anodicallyetched in 10% nitric acid, the alloy being made the positive electrodeand platinum being made the cathode, although the metal used for thecathode is not critical. An anodic current was applied to the nitricacid until the alloy was cleaned. The cleaned alloy was immediatelyrinsed in distilled water and much of the excess moisture wiped off. Asmall amount of moisture was permitted to remain on the cleaned alloysurface. The alloy, with moisture on its surface, was then dipped intoan amalgam containing 0.5% of an alkali metal, sodium, for a period ofabout 20 seconds. An amalgam formed, the alkali metal contained withinthe amalgam reacting with the moisture on the alloy surfaces to releasehydrogen. An extremely shock-resistant and adhering amalgam resulted.

EXAMPLE V The procedure used was similar to that described in Example IVexcept the alloy was 52 nickel-48 iron and a 25% nitric acid anodicsolution was used.

The concentration of the acid used is not critical. Concentrated acidmay even be used so long as the cleaned alloy is immediately rinsed indistilled waterv and the excess water shaken off the piece to beamalgamated. The piece to be amalgamated cannot be completely free frommoisture as abovedescribed.

Sulphuric acid may be substituted for nitric acid or hydrochloric acid,the solubility of the cathode in the acid being a major consideration.Since I have provided means for amalgamating substantially pure iron,the nickel in the nickel-iron alloy can range from a trace amount allthe way up to Several examples of other ferrous alloys amalgamated inaccordance with my invention are presented below:

EXAMPLE VI A 9.5 nickel-balance substantially iron (about 1% of carbon,manganese, chromium, copper, and molybdenum) alloy wire was cleaned bydipping in 50% nitric acid,

EXAMPLE VII The procedure used here was generally similar to thatdescribed under Example VI except the alloy comprised 77.4% copper,13.3% iron, 3.7% molybdenum, 5.0% copper, and 0.4% of trace metals.

EXAMPLE VIII The procedure used was substantially identical to thatdescribed under Example VI except the alloy used was a 3%97% iron alloy.The alkali metals to be used with the amalgam are not limited to sodiumand potassium. For example, cesium and rubidium in the range of about0.01 to 1.0% by weight of the mercury may successfully be used. Ifexcess alkali metal is present in the amalgam, it will either float tothe top of the mercury or precipitate. In either case, the amalgam isnot deleteriously effected.

From the data above, it is expected that iron-nickel and iron copperalloys may readily be amalgamated wherein the iron content varies from100% to only a trace amount of either copper or nickel or both.

In all examples, the amalgam is desirably covered with kerosene, or thelike, to prevent the alkali metal in the amalgam from oxidizing, or theamalgam is maintained in contact with an inert gas. Further, in theevent the acidcleaned alloy is inadvertently dried completely, it isonly necessary to re-dip it in distilled water and Wipe off the excesswater before immersion into the amalgam.

I claim:

1. Process for amalgamating a metallic material selected from the groupconsisting of iron, platinum, and iron alloys, comprising the steps of:

cleaning said material with acid;

wetting said cleaned material to insure presence of moisture on surfacesthereof;

dipping said material having moistened surfaces into an amalgamatedcomprising an alkali metal and mercury to produce said amalgamatedmaterial.

2. The process as described in claim 1 wherein said metallic material issubstantially pure iron.

3. The process as described in claim 1 wherein said metallic material issubstantially pure platinum.

4. The process as described in claim 1 wherein said metallic material isa ferrous alloy.

5. The process as described in claim 1 wherein said acid is selectedfrom the group consisting of hydrochloric, nitric, and sulphuric, andthe concentration of said acids range from about 1% to concentrated.

6. The process as described in claim 1 wherein said amalgam comprisesabout 0.01 to 1.0 weight percent of said alkali metal and wherein saidalkali metal is selected from the group consisting of sodium, potassium,cesium and rubidium.

7. The process as described in claim 1 wherein said iron alloy comprisesonly trace amounts of a metal selected from the group consisting ofnickel, copper, and nickel and copper.

8. The process as described in claim 1 wherein said iron alloy isselected from the group consisting essentially of, by weight percent, 45nickel and iron; 52 nickel and 48 iron; 9.5 nickel, balancesubstantially iron; and 77.4 copper, 13.3 iron, 3.7 molybdenum, 5.0copper and 0.4 trace metals.

9. The process as described in claim 1, wherein said wetting stepcomprises allowing at least a trace of the moisture adhering on saidmaterial from said cleaning step to remain thereon prior to said dippingstep.

10. The process as described in claim 1, wherein said wetting stepcomprises contacting said material with distilled water and allowing atleast a trace of said water to remain thereon prior to said dippingstep.

References Cited UNITED STATES PATENTS 71,307 11/1867 Johnston -169X2,547,536 4/1951 Pollard 148-16X 2,784,061 3/1957 Cunningham 75--169X2,850,382 9/1958 Kelly 75-169 3,154,413 10/1964 Dow 75-135 3,182,9845/1965 Gilbert 75-l69X HYLAND BIZOT, Primary Examiner J. E. LEGRU,Assistant Examiner U.S. c1. X.R 75-135, 169, 172; 14816

